Block device for managing a Master Boot Record https://en.wikipedia.org/wiki/Master_boot_record. More...

#include <MBRBlockDevice.h>

Public Member Functions
	MBRBlockDevice (BlockDevice *bd, int part)
	Lifetime of the block device.
virtual	~MBRBlockDevice ()
	Lifetime of the block device.
virtual int	init ()
	Initialize a block device.
virtual int	deinit ()
	Deinitialize a block device.
virtual int	sync ()
	Ensure data on storage is in sync with the driver.
virtual int	read (void *buffer, bd_addr_t addr, bd_size_t size)
	Read blocks from a block device.
virtual int	program (const void *buffer, bd_addr_t addr, bd_size_t size)
	Program blocks to a block device.
virtual int	erase (bd_addr_t addr, bd_size_t size)
	Erase blocks on a block device.
virtual bd_size_t	get_read_size () const
	Get the size of a readable block.
virtual bd_size_t	get_program_size () const
	Get the size of a programmable block.
virtual bd_size_t	get_erase_size () const
	Get the size of an erasable block.
virtual bd_size_t	get_erase_size (bd_addr_t addr) const
	Get the size of an erasable block given address.
virtual int	get_erase_value () const
	Get the value of storage when erased.
virtual bd_size_t	size () const
	Get the total size of the underlying device.
virtual bd_addr_t	get_partition_start () const
	Get the offset of the partition on the underlying block device.
virtual bd_addr_t	get_partition_stop () const
	Get size of partition on underlying block device.
virtual uint8_t	get_partition_type () const
	Get 8-bit type of the partition.
virtual int	get_partition_number () const
	Get the partition number.
virtual int	trim (bd_addr_t addr, bd_size_t size)
	Mark blocks as no longer in use.
bool	is_valid_read (bd_addr_t addr, bd_size_t size) const
	Convenience function for checking block read validity.
bool	is_valid_program (bd_addr_t addr, bd_size_t size) const
	Convenience function for checking block program validity.
bool	is_valid_erase (bd_addr_t addr, bd_size_t size) const
	Convenience function for checking block erase validity.
Static Public Member Functions
static int	partition (BlockDevice *bd, int part, uint8_t type, bd_addr_t start)
	Format the MBR to contain the following partition.
static int	partition (BlockDevice *bd, int part, uint8_t type, bd_addr_t start, bd_addr_t stop)
	Format the MBR to contain the following partition.

Detailed Description

Block device for managing a Master Boot Record https://en.wikipedia.org/wiki/Master_boot_record.

Here is an example of partitioning a heap backed block device

  #include "mbed.h"
  #include "HeapBlockDevice.h"
  #include "MBRBlockDevice.h"

  // Create a block device with 64 blocks of size 512
  HeapBlockDevice mem(64*512, 512);

  // Partition into two partitions with ~half the blocks
  MBRBlockDevice::partition(&mem, 1, 0x83, 0*512, 32*512);
  MBRBlockDevice::partition(&mem, 2, 0x83, 32*512);

  // Create a block device that maps to the first 32 blocks (excluding MBR block)
  MBRBlockDevice part1(&mem, 1);

  // Create a block device that maps to the last 32 blocks
  MBRBlockDevice part2(&mem, 2);

Here is a more realistic example where the MBRBlockDevice is used to partition a region of space on an SD card. When plugged into a computer, the partitions will be recognized appropriately.

  #include "mbed.h"
  #include "SDBlockDevice.h"
  #include "MBRBlockDevice.h"
  #include "FATFileSystem.h"

  // Create an SD card
  SDBlockDevice sd(s0, s1, s2, s3);

  // Create a partition with 1 GB of space
  MBRBlockDevice::partition(&sd, 1, 0x83, 0, 1024*1024);

  // Create the block device that represents the partition
  MBRBlockDevice part1(&sd, 1);

  // Format the partition with a FAT filesystem
  FATFileSystem::format(&part1);

  // Create the FAT filesystem instance, files can now be written to
  // the FAT filesystem in partition 1
  FATFileSystem fat("fat", &part1);

Note:

The MBR partition table is relatively limited:

At most 4 partitions are supported
Extended partitions are currently not supported and will error during init

Definition at line 91 of file MBRBlockDevice.h.

Constructor & Destructor Documentation

MBRBlockDevice	(	BlockDevice *	bd,
		int	part
	)

Lifetime of the block device.

Parameters:

bd	Block device to back the MBRBlockDevice
part	Partition to use, 1-4

Definition at line 182 of file MBRBlockDevice.cpp.

virtual ~MBRBlockDevice ( ) [virtual]

Lifetime of the block device.

Definition at line 133 of file MBRBlockDevice.h.

Member Function Documentation

int deinit ( ) [virtual]

Deinitialize a block device.

Returns:: 0 on success or a negative error code on failure

Implements BlockDevice.

Definition at line 236 of file MBRBlockDevice.cpp.

int erase	(	bd_addr_t	addr,
		bd_size_t	size
	)		`[virtual]`

Erase blocks on a block device.

The state of an erased block is undefined until it has been programmed, unless get_erase_value returns a non-negative byte value

Parameters:

addr	Address of block to begin erasing
size	Size to erase in bytes, must be a multiple of erase block size

Returns:: 0 on success, negative error code on failure

Reimplemented from BlockDevice.

Definition at line 258 of file MBRBlockDevice.cpp.

bd_size_t get_erase_size ( ) const [virtual]

Get the size of an erasable block.

Returns:: Size of an erasable block in bytes

Note:: Must be a multiple of the program size

Reimplemented from BlockDevice.

Definition at line 274 of file MBRBlockDevice.cpp.

bd_size_t get_erase_size ( bd_addr_t addr ) const [virtual]

Get the size of an erasable block given address.

Parameters:

addr	Address within the erasable block

Returns:: Size of an erasable block in bytes

Note:: Must be a multiple of the program size

Reimplemented from BlockDevice.

Definition at line 279 of file MBRBlockDevice.cpp.

int get_erase_value ( ) const [virtual]

Get the value of storage when erased.

If get_erase_value returns a non-negative byte value, the underlying storage is set to that value when erased, and storage containing that value can be programmed without another erase.

Returns:: The value of storage when erased, or -1 if you can't rely on the value of erased storage

Reimplemented from BlockDevice.

Definition at line 284 of file MBRBlockDevice.cpp.

int get_partition_number ( ) const [virtual]

Get the partition number.

Returns:: The partition number, 1-4

Definition at line 309 of file MBRBlockDevice.cpp.

bd_size_t get_partition_start ( ) const [virtual]

Get the offset of the partition on the underlying block device.

Returns:: Offset of the partition on the underlying device

Definition at line 294 of file MBRBlockDevice.cpp.

bd_size_t get_partition_stop ( ) const [virtual]

Get size of partition on underlying block device.

Returns:: Size of the partition on the underlying device

Definition at line 299 of file MBRBlockDevice.cpp.

uint8_t get_partition_type ( ) const [virtual]

Get 8-bit type of the partition.

Returns:: 8-bit type of partition assigned during format

Definition at line 304 of file MBRBlockDevice.cpp.

bd_size_t get_program_size ( ) const [virtual]

Get the size of a programmable block.

Returns:: Size of a programmable block in bytes

Note:: Must be a multiple of the read size

Implements BlockDevice.

Definition at line 269 of file MBRBlockDevice.cpp.

bd_size_t get_read_size ( ) const [virtual]

Get the size of a readable block.

Returns:: Size of a readable block in bytes

Implements BlockDevice.

Definition at line 264 of file MBRBlockDevice.cpp.

int init ( ) [virtual]

Initialize a block device.

Returns:: 0 on success or a negative error code on failure

Implements BlockDevice.

Definition at line 188 of file MBRBlockDevice.cpp.

bool is_valid_erase	(	bd_addr_t	addr,
		bd_size_t	size
	)		const `[inherited]`

Convenience function for checking block erase validity.

Parameters:

addr	Address of block to begin erasing
size	Size to erase in bytes

Returns:: True if erase is valid for underlying block device

Definition at line 213 of file BlockDevice.h.

bool is_valid_program	(	bd_addr_t	addr,
		bd_size_t	size
	)		const `[inherited]`

Convenience function for checking block program validity.

Parameters:

addr	Address of block to begin writing to
size	Size to write in bytes

Returns:: True if program is valid for underlying block device

Definition at line 199 of file BlockDevice.h.

bool is_valid_read	(	bd_addr_t	addr,
		bd_size_t	size
	)		const `[inherited]`

Convenience function for checking block read validity.

Parameters:

addr	Address of block to begin reading from
size	Size to read in bytes

Returns:: True if read is valid for underlying block device

Definition at line 185 of file BlockDevice.h.

int partition	(	BlockDevice *	bd,
		int	part,
		uint8_t	type,
		bd_addr_t	start,
		bd_addr_t	stop
	)		`[static]`

Format the MBR to contain the following partition.

Parameters:

bd	Block device to partition
part	Partition to use, 1-4
type	8-bit partition type to identitfy partition's contents
start	Start block address to map to block 0 of partition, negative addresses are calculated from the end of the underlying block devices. Block 0 is implicitly ignored from the range to store the MBR.
stop	End block address to mark the end of the partition, this block is not mapped, negative addresses are calculated from the end of the underlying block device.

Returns:: 0 on success or a negative error code on failure

Definition at line 151 of file MBRBlockDevice.cpp.

int partition	(	BlockDevice *	bd,
		int	part,
		uint8_t	type,
		bd_addr_t	start
	)		`[static]`

Format the MBR to contain the following partition.

Parameters:

bd	Block device to partition
part	Partition to use, 1-4
type	8-bit partition type to identitfy partition's contents
start	Start block address to map to block 0 of partition, negative addresses are calculated from the end of the underlying block devices. Block 0 is implicitly ignored from the range to store the MBR.

Returns:: 0 on success or a negative error code on failure

Note:: This is the same as partition(bd, part, type, start, bd->size())

Definition at line 121 of file MBRBlockDevice.cpp.

int program	(	const void *	buffer,
		bd_addr_t	addr,
		bd_size_t	size
	)		`[virtual]`

Program blocks to a block device.

The blocks must have been erased prior to being programmed

Parameters:

buffer	Buffer of data to write to blocks
addr	Address of block to begin writing to
size	Size to write in bytes, must be a multiple of program block size

Returns:: 0 on success, negative error code on failure

Implements BlockDevice.

Definition at line 252 of file MBRBlockDevice.cpp.

int read	(	void *	buffer,
		bd_addr_t	addr,
		bd_size_t	size
	)		`[virtual]`

Read blocks from a block device.

Parameters:

buffer	Buffer to read blocks into
addr	Address of block to begin reading from
size	Size to read in bytes, must be a multiple of read block size

Returns:: 0 on success, negative error code on failure

Implements BlockDevice.

Definition at line 246 of file MBRBlockDevice.cpp.

bd_size_t size ( ) const [virtual]

Get the total size of the underlying device.

Returns:: Size of the underlying device in bytes

Implements BlockDevice.

Definition at line 289 of file MBRBlockDevice.cpp.

int sync ( ) [virtual]

Ensure data on storage is in sync with the driver.

Returns:: 0 on success or a negative error code on failure

Reimplemented from BlockDevice.

Definition at line 241 of file MBRBlockDevice.cpp.

virtual int trim	(	bd_addr_t	addr,
		bd_size_t	size
	)		`[virtual, inherited]`

Mark blocks as no longer in use.

This function provides a hint to the underlying block device that a region of blocks is no longer in use and may be erased without side effects. Erase must still be called before programming, but trimming allows flash-translation-layers to schedule erases when the device is not busy.

Parameters:

addr	Address of block to mark as unused
size	Size to mark as unused in bytes, must be a multiple of erase block size

Returns:: 0 on success, negative error code on failure

Definition at line 120 of file BlockDevice.h.

Type:	Program
Mbed OS support:	Mbed OS
Created:	29 Mar 2018
Imports:	22
Forks:	0
Commits:	5
Dependents:	0
Dependencies:	0
Followers:	6

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